Which engine cover are you talking about? If you're talking about the generator cover, you may want to disconnect your battery before you pull it off. There is no spring holding it on, that is just the electromagnetic fields holding it in place. You do have to give it a good tug, but be careful. Also, when you put the cover back on, try not to have your fingers between the cover and the engine. Those same fields will yank the cover right out of your hands.